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Bleed off from Cooling tower

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Bleed off from Cooling tower

Bleed off from Cooling tower

sridhar1312

(Mechanical)

(OP)

16 Dec 09 02:35

Is there any formula to ascertain the bleed off recommended for cooling towers to ensure concentration build up in the cooling water system.We find many of the cooling towers does not have the provision for bleed off thereby the refrigeration system operates almost same condensing temperature as the Air cooled condition.
What is optimum quality of water recommended for the Cooling tower.

RE: Bleed off from Cooling tower

BM4BRANES

(Mechanical)

16 Dec 09 16:18

Uh oh, sounds like the immediate problem is scale build up. Installing a bleed valve now will not undo years of differed maintenance.

After you have resolved the scale(heat transfer) problem, or installed a new tower, a bleed valve needs to be installed. Once you establish the Cycles of Concentration, you might try this: "Bleed rate" = "evap rate"(1.8gal/hr/to) / "cycles of concentration". good luck.
 

RE: Bleed off from Cooling tower

DRWeig

(Electrical)

17 Dec 09 12:04

Or, once you've installed the bleed valve as BM4BRANES suggests, put in a conductivity transmitter and controller. Find the optimum setting by consulting with whoever sells treatment chemicals in your area (but watch out for the sales pitch).

Good on ya,

Goober Dave

RE: Bleed off from Cooling tower

RossABQ

(Mechanical)

The company is the world’s best motor for cooling tower fan supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

25 Dec 09 19:38

Most controllers are set for 1,000 - 1,200 micromhos conductivity, depending on the water chemistry and the amounts/types of minerals.  I agree tho, water chemistry isn't the only problem here.  It sounds like the air is bypassing around the fill, or air flow is inadequate.

RE: Bleed off from Cooling tower

atlas06

(Mechanical)

9 Jan 10 15:53

try looking into the dolphin water treatment system if no one wants to deal with chemical treatment.

incidently, I have read case studies and all on the Dolphin water treatment system and it appears to sell good. Even ASHRAE green tips list it as an energy and water saving system.

Question, does anyone out there has good experience with it? sorry sridhar if this is a highjack of your post, but I think it is relevant to your post.

RE: Bleed off from Cooling tower

sridhar1312

(Mechanical)

(OP)

10 Jan 10 02:54

Attention: atlas06

Haven't come across dolphin system can you send link please

RE: Bleed off from Cooling tower

atlas06

(Mechanical)

10 Jan 10 16:24 http://www.clearwater-dolphin.com/market_research.htm
Yiu ought to develop the instinct to google out things.
Smile - :)

Yiu ought to develop the instinct to google out things.Smile - :)

RE: Bleed off from Cooling tower

RossABQ

(Mechanical)

10 Jan 10 22:30 NO positive remarks, I can assure you!  The people who are "accepting" it don't have to live with its failings.   

Atlas, ought to search on this forum for several threads about the Dolphin system!NO positive remarks, I can assure you! The people who are "accepting" it don't have to live with its failings.

RE: Bleed off from Cooling tower

cjw81

(Mechanical)

17 Jan 10 21:59

My advice, you should get a professional in to make an analysis of your system. you should get only a licensed guy to perform the work. They should have a pesticide applicators license.it does sound like you have multiple problems with the system. Do not take the  possibility of legionella lightly.
 

RE: Bleed off from Cooling tower

imok2

(Mechanical)

18 Jan 10 17:38

Chemical savings are directly proportional to water savings. For a 10,000 gpm open recirculating system with a 10o D T.
Increasing from 3 to 5 cycles gives 85% of the water and chemical savings you would receive if the cycles were increased from 2 to 10.

As cycles increase, so does the fouling potential in the system. Suspended solids and contaminants also increase with the increased cycles of concentration. It is usually best to limit cycles at or below 5. Further increase does not result in significant makeup water and treatment chemical savings and may not warrant the possibility of deposit formation and system fouling.

Remember, only when water savings are of paramount importance should cycles be allowed to approach theoretical limits. Other safe and effective levels are the best.

 
 

RE: Bleed off from Cooling tower

mauricestoker

(Mechanical)

19 Jan 10 08:38

Atlas,

I've had a few physical water treatment salesman make their pitch. Pretty much the NIMBY repsonse, Not In My Bundle-Your's? I've spoken with a lot of plant operators, when we get to details, the answer has been that the water chemistry is not suitable.

RE: Bleed off from Cooling tower

MFranklin

(Mechanical)

31 Jan 10 19:06

3 gallons of water at minute for every 100 tons of capacity.
This is in addition to make up for carry over.  Which is also 3gpm/100t.  A rule of thumb from the ammonia refrigeration trade.  

RE: Bleed off from Cooling tower

marcoh

(Mechanical)

2 Feb 10 06:53

All depends on the quality of the makeup water and how much dust is taken in.  A well designed system with good quality water should achieve 5 or 6 cycles of concentration.  You should talk to a local water treatment specialist who should know local water quality.

Of course your cooling towers need to be well maintained, have clean fill, clean basins, float valves that don't leak, side stream filtration systems etc all of which will affect performance.

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News

Water Levels Important Issue in Operation of Cooling Towers

One of the biggest issues in cooling-tower operation is keeping the proper quantity of circulating water in the system. After water passes through the tower, it collects in the basin and returns to the circulating pumps. If the water level is too low, the pumps suck in air. If the water level is too high, the water overflows, creating roof damage and possible leaks.

Technicians can make up for water loss by adding water to the basin. In most towers, a float valve helps maintain a certain level of water. While float valves are simple to operate, they can malfunction, typically in the open position, allowing too much water to enter the basin. An alternative to the float valve is an electronic level control that maintains water levels between a minimum and maximum position.

Regardless of the system installed, technicians should monitor water levels in the tower basin daily to ensure proper operation. Since cooling towers can be a major source of water use, technicians should install a meter on the makeup-water line. By reading this meter daily or weekly, technicians can identify developing problems within the tower.

James Piper, P.E., is a national consultant based in Bowie, Md. He has more than 25 years of experience in facilities maintenance and management issues.

For more information, please visit benefits of cooling water.

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